KR101156388B1 - Refrigerator oil composition - Google Patents

Abstract

The present invention relates to a base oil comprising at least one selected from (A) polyalkylene glycol, polyol ester, poly-α-olefin, alkylbenzene and mineral oil, (B) an organic sulfur compound having a content of sulfur of 35% by mass or less, and ( C) A refrigerator oil composition containing a refrigerant comprising at least one selected from carbon dioxide, hydrocarbons and ammonia, wherein the total sulfur content is from 0.01 to 0.1% by mass relative to the total amount of the component (A) and the component (B). As the oil composition, there is provided a novel refrigeration oil composition which is free from environmental problems such as destruction of the ozone layer and global warming, and which can maintain lubrication performance for a long time and does not block the capillary tube in the refrigeration cycle.

Refrigerator oil composition, base oil, organic sulfur compound, refrigerant

Description

Refrigerator oil composition {REFRIGERATOR OIL COMPOSITION}

The present invention relates to a novel refrigerator oil composition, and in particular to a refrigerator oil composition excellent in lubricity using a natural refrigerant.

In general, a compression refrigeration cycle of a refrigeration refrigerator including a refrigerator, for example, a compressor, a condenser, an expansion valve, and an evaporator, has a structure in which a mixed liquid of refrigerant and lubricating oil circulates in the sealed system. In such a compressor, chlorofluorocarbons such as dichlorodifluoromethane (R-12) and chlorodifluoromethane (R-22) have conventionally been used as refrigerants, and many lubricants used in combination therewith are produced. Has been used. These fluorocarbon compounds, which have been conventionally used as refrigerants, may cause environmental pollution such as destroying the ozone layer present in the stratosphere when released into the atmosphere, and thus, as new refrigerants, 1,1,1,2-tetra Hydrofluorocarbons and fluorocarbons represented by fluoroethane (R-134a) have come to be used. The hydrofluorocarbons and the like have no fear of destroying the ozone layer, but because of their long life in the atmosphere, there is concern about the effects of global warming. In recent years, use of natural refrigerants without such problems has been considered.

On the other hand, in the refrigerator oil composition, a phosphorous additive represented by tricresyl phosphate (TCP) was used as an extreme pressure agent. However, there has been a problem that the phosphorus extreme pressure agent is deteriorated and sludged by thermal decomposition, hydrolysis, and tribolic chemical reaction on the friction surface. In addition, since the phosphorous additive is consumed by being deteriorated and sludged, lubrication performance for a long time cannot be maintained, leading to crushing and abrasion.

In a lubricating oil composition for a refrigerator using a conventional fluorocarbon refrigerant, sulfur is contained by adding an organic sulfur compound, having excellent heat resistance and abrasion resistance, low viscosity change with respect to temperature change, and excellent fluorocarbon solubility. Lubricant oil has been proposed (Japanese Patent Laid-Open No. 58-103594). According to Japanese Patent Application Laid-Open No. 58-l03594, the content of an organic sulfur compound is important in the lubricating oil composition for a fluorocarbon refrigerator, and the organic sulfur compound is naturally contained in mineral oil when mineral oil is used as a base oil. It is said to exist as an enemy. However, in the lubricating oil composition for refrigerators using natural refrigerants, sufficient abrasion resistance and extreme pressure cannot be imparted only by controlling the sulfur content.

This invention is made | formed in order to solve the said subject, Comprising: It aims at providing the lubricating oil composition for refrigerators using the natural refrigerant which can maintain lubrication performance for a long time, and does not block the capillary tube in a refrigeration cycle.

As a result of intensive studies to develop a lubricating oil composition for a refrigerator having the above characteristics, the present inventors found that a refrigerator oil containing a specific organic sulfur compound in a specific base oil can maintain lubricating performance for a long time when using a natural refrigerant. It was found that the capillary in the freezing cycle was not blocked. The present invention has been completed based on these findings.

That is, the present invention relates to an organic sulfur compound having a content of 35% by mass or less of a base oil containing at least one selected from (A) polyalkylene glycol, polyol ester, poly-α-olefin, alkylbenzene and mineral oil, and (B) sulfur. And (C) a refrigerant oil composition comprising a refrigerant selected from carbon dioxide, hydrocarbons and ammonia, wherein the total sulfur content is 0.01 to 0.1% by mass relative to the total amount of the component (A) and the component (B). It is to provide a phosphorus refrigeration oil composition.

1 is a view showing a capillary clogging tester.

Explanation of symbols for the main parts of the drawings

1: capillary blockage tester

2: compressor

2A: compressor inlet

2B: compressor outlet

3: capillary

3A: capillary inlet

3B: capillary outlet

4: high temperature side flow path

5: low temperature side flow path

6: heat exchanger

7: discharge pressure gauge

8: suction pressure gauge

9: Valve for connecting vacuum pump

10: simulated circulatory system

BEST MODE FOR CARRYING OUT THE INVENTION [

The lubricating oil composition of the present invention uses (A) at least one selected from polyalkylene glycol, polyol ester, poly-α-olefin, alkylbenzene and mineral oil.

As polyalkylene glycol, what is represented by following formula (I) is preferable.

R ¹ -[(OR ² ) _m -OR ³ ] _n

Here, R ¹ is hydrogen, an alkyl group having 1 to 10 carbon atoms, an acyl group or an aliphatic hydrocarbon group having 2 to 6 bonding sites, R ² is an alkylene group having 2 to 4 carbon atoms, and may be any one of a homopolymer and a copolymer. R <^3> is hydrogen, a C1-C10 alkyl group or acyl group, n is an integer of 1-6, m is an integer whose average value of m * n becomes 6-80.

The alkyl group may be any of linear, branched and cyclic. As a specific example of the said alkyl group, a methyl group, an ethyl group, n-propyl group, isopropyl group, various butyl groups, various pentyl groups, various hexyl groups, cyclopentyl group, cyclohexyl group, etc. are mentioned. As carbon number of the said alkyl group, it is preferable that it is 10 or less, and when it is 10 or less, sufficient compatibility with a refrigerant is obtained.

In addition, the alkyl portion of the acyl group may be any of linear, branched and cyclic. Specific examples of the alkyl portion of the acyl group include methyl group, ethyl group, n-propyl group, isopropyl group, various butyl groups, various pentyl groups, various hexyl groups, cyclopentyl groups, cyclohexyl groups and the like. It is preferable that carbon number of the said acyl group is also 10 or less similarly to an alkyl group, and when it is 10 or less, sufficient compatibility with a refrigerant will be obtained.

R ¹ and R ³ may be the same or different from each other. In the present invention, in the polyalkylene glycol represented by the above formula (I), one of R ¹ or R ³ is hydrogen, and the other is an alkyl group, and the alkyl group is an alkyl group having 1 to 3 carbon atoms, especially a methyl group. The case is preferred. Moreover, the case where both R <^1> and R <^3> is a C1-C3 alkyl group is also preferable, especially when both R <^1> and R <^3> are a methyl group. As a base oil of this invention, multiple types of polyalkylene glycol can be mixed and used.

As a polyol ester, the carboxylic acid ester of the polyhydric hydroxy compound containing two or more hydroxyl groups is mentioned, For example, what is represented by following formula (II) is preferable.

R ⁴ [OCOR ⁵ ] _f

Herein, R ⁴ represents a hydrocarbon group, R ⁵ represents a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms, f represents an integer of 2 to 6, and a plurality of [OCOR ⁵ ] s may be the same or different.

In the general formula (II), the hydrocarbon group represented by R ⁴ may be either linear or branched, preferably an alkyl group having 2 to 10 carbon atoms. R ⁵ is a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms, preferably an alkyl group having 2 to 16 carbon atoms. The polyol ester represented by the above formula (II) can be obtained by reacting a polyhydric alcohol represented by the following formula (III) with a carboxylic acid represented by the following formula (IV) or a reactive derivative such as an ester thereof or an acid halide.

R ⁴ (OH) _f

(Wherein R ⁴ and f are the same as above)

R ⁵ COOH

(Wherein R ⁵ is the same as above)

As the polyhydric alcohol represented by the above formula (III), various ones can be used, for example, ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, trimethylol ethane, trimethylol propane, glycerin, pentaerythritol, dipentaerythritol And sorbitol. The carboxylic acid represented by the general formula (IV) is not particularly limited, but for example, propionic acid, butyric acid, pivalic acid, valeric acid, caproic acid, heptanoic acid, 3-methylhexanoic acid, 2-ethylhexanoic acid and caprylic acid , Pelagonic acid, decanoic acid, lauryl acid, myristic acid, palmitic acid and the like. As a base oil of this invention, multiple types of polyol ester can be mixed and used.

The poly-α-olefin is an oligomer of an α-olefin having about 3 to 12 carbon atoms, preferably a molecular weight of 200 to 5000, and more preferably 300 to 2000. As a base oil of this invention, multiple types of poly-alpha-olefin can be mixed and used.

Alkylbenzene is obtained by polymerization of aromatics such as benzene, toluene, xylene, ethylbenzene, methylethylbenzene, diethylbenzene, and mixtures thereof with lower monoolefins such as ethylene, propylene, butene and isobutylene, and propylene. Branched olefins having 6 to 40 carbon atoms, such as branched olefins, waxes, heavy oils, petroleum distillates, polyethylene and polypropylene, are alkylated with an alkylating agent. The number of alkyl groups of the benzene of the alkylbenzene is 1 to 3, and it is particularly preferable to contain a large amount of alkylbenzene having two alkyl groups. In addition, as a base oil of this invention, multiple types of alkylbenzene can be mixed and used.

The mineral oil to be used as the base oil of the present invention is not particularly limited, and paraffinic mineral oil, naphthenic mineral oil and the like can be mentioned, but the sulfur content is preferably 200 mass ppm or less. Although sulfur content in mineral oil changes with sulfur content in the crude oil used as a raw material, it is preferable to refine | purify so that it may become 200 mass ppm or less. As the base oil of the present invention, plural kinds of mineral oils can be mixed and used.

As mentioned above, although the above-mentioned thing is used preferably as (A) base oil used by this invention as mentioned above, polyalkylene glycol, polyol ester, poly-alpha-olefin, and alkylbenzene are especially preferable from a viewpoint of stability and the amount of evaporation reduction. In addition, these can be used individually by 1 type or in mixture of 2 or more types.

It is preferable that the (A) base oil used by this invention is 3-1000 mm <2> / s of kinematic viscosity in 40 degreeC. If it is 3 mm <2> / s or more, sufficient lubrication performance will be obtained, and if it is 1000 mm <2> / s or less, an excessive load will not be applied and energy efficiency will become high. In view of the above, the kinematic viscosity at 40 ° C of the base oil is preferably in the range of 5 to 500 mm 2 / s, more preferably in the range of 5 to 150 mm 2 / s.

Next, in this invention, it is characterized by containing the organic sulfur compound whose content of sulfur is 35 mass% or less as (B) component. When content of sulfur exceeds 35 mass%, deterioration and sludge formation may occur. Specifically, polysulfides such as three or more sulfurs contained in one molecule have this risk. Moreover, since the content of sulfur is more than 5 mass%, it is preferable at the point which can reduce the addition amount of (B) component.

Examples of the organic sulfur compound (B) preferably used in the present invention include an aliphatic sulfur compound, a heterocyclic sulfur compound, and an aromatic sulfur compound.

As an aliphatic sulfur compound, it is preferable that carbon number is 12 or more, Furthermore, it is preferable that it is 14 or more, especially 18 or more. Specifically, dioctyl sulfide, dididodecyl sulfide, ditetradecyl sulfide, etc. are mentioned.

The heterocyclic sulfur compound preferably has 8 or more carbon atoms, more preferably 10 or more carbon atoms, and more preferably 12 or more carbon atoms. Specifically, benzothiophene, dibenzothiophene, phenothiazine, benzothiapyran, thiapyran, thianthrene, dibenzothiapyran, diphenylene disulfide, and these alkyl derivatives are mentioned.

As an aromatic sulfur compound, it is preferable that carbon number is 12 or more, and it is more preferable that it is 16 or more. Specifically, 4,4'- thiobis (3-methyl-6- t-butylphenol), diphenyl sulfide, dioctyl diphenyl sulfide, dialkyl diphenylene sulfide, etc. are mentioned.

In addition, an organic sulfur compound other than an aliphatic sulfur compound, a heterocyclic sulfur compound, and an aromatic sulfur compound having 8 or more carbon atoms may be used, and for example, 8 or more carbon atoms, preferably 10 or more carbon atoms, And organic sulfur compounds containing one or more S atoms. Specific examples thereof include sulfolane, diphenyl sulfoxide, diphenyl sulfone, thiazole, thiazole derivatives, thiaadamantane, 2-thienylcarbinol, Thiophene acetic acid etc. are mentioned.

Among the above organic sulfur compounds, diphenylenedisulfide, phenothiazine and dialkyldiphenylene sulfide are preferably used.

Sulfur content in the refrigerator oil composition of this invention makes it essential that it is 0.01-0.1 mass% based on the total amount of (A) component and (B) component. If the said sulfur content is 0.01 mass% or more, sufficient lubrication performance cannot be achieved, and if it is 0.1 mass% or less, generation | occurrence | production of sludge by alteration etc. can fully be suppressed. In view of the above, the sulfur content is preferably in the range of 0.02 to 0.05 mass%, more preferably in the range of 0.025 to 0.035 mass%.

In addition, it is preferable to mix | blend the additive normally used with refrigeration oil composition with the lubricating oil composition of this invention, and it is especially preferable to add antioxidant, an acid trapping agent, and an antifoamer.

There is no restriction | limiting in particular as antioxidant, For example, a phenolic antioxidant, an amine antioxidant, etc. can be used. The acid trapping agent is blended for the purpose of hydrolysis stability in the refrigeration oil composition, for example, phenylglycidyl ether, alkyl glycidyl ether, alkylene glycol glycidyl ether, cyclohexene oxide, α Epoxy compounds, such as an olefin oxide and epoxidized soybean oil, are mentioned. Among them, phenylglycidyl ether, alkylglycidyl ether, alkylene glycol glycidyl ether, cyclohexene oxide and α-olefin oxide are preferable from the viewpoint of compatibility. Examples of the antifoaming agent include silicone oil and silicon fluoride oil.

Moreover, other additives, for example, copper inactivating agents, such as benzotriazole and its derivative (s), can be added in the range which does not impair the objective of this invention. These additives are usually added in the range of 0.005-5 mass%, respectively.

The refrigerant used in the lubricating oil composition of the present invention includes at least one selected from carbon dioxide gas, hydrocarbons and ammonia. Hydrocarbon is used here normally as a refrigerant | coolant, For example, propane, butane, a mixture thereof, etc. are mentioned.

The content of these refrigerants in the refrigerator oil composition is usually in the range of 10 to 99 mass%. If it is 10 mass% or more, sufficient freezing capability can be exhibited, and if it is 99 mass% or less, sufficient quantity of lubricating oil exists and there is no problem of seizure and abrasion. In the above aspect, the range of 30-95 mass% is more preferable.

The refrigeration oil composition of the present invention can be used for various purposes, for example, for air conditioning, refrigerator, gas heat pump (GHP), vending machine, showcase refrigeration, car air conditioner, hot water supply, floor heating, and the like. Can be used.

Next, although an Example demonstrates this invention still in detail, this invention is not limited at all by these examples.

(Assessment Methods)

1.Shield tube test (thermal stability)

A refrigeration oil composition prepared by the method described in each of Examples and Comparative Examples was placed in a 10 ml glass tube, and metal catalysts of copper, aluminum, and iron were added thereto. After the glass tube was sealed and kept at 175 ° C for 30 days, the appearance of the refrigerator oil composition, the appearance of copper, and the presence of sludge were evaluated.

2. Sealed Parex Test (Lubrication)

Abrasion amount (mg) was calculated | required in accordance with ASTM D2670 using the closed Parex friction tester. On the other hand, test conditions were load 1335 N, rotation speed 300 rpm, temperature 80 degreeC, test time 1 hour, and the used pin was AISIC1137 and the block was SAE3135.

3. Capillary blockage test

It evaluated by the rate of fall of the capillary flow volume after 1000 hours using the tester shown in FIG. This test apparatus 1 is disclosed in Japanese Patent Laid-Open No. 11-183334, which is a compressor 2, a capillary tube 3 as a means for reducing temperature and pressure, a discharge port 2A of the compressor 2 and a capillary tube 3 The high temperature side flow passage 4 for communicating the inlet 3A, the low temperature side flow passage 5 for communicating the outlet 3B of the capillary tube 3, and the suction port 2B of the compressor 2, and the high temperature side flow passage 4. ) And a heat exchanger 6 provided in the middle of the low temperature side flow path 5 and performing heat exchange between refrigerants between the respective flow paths 4 and 5, and the compressor 2 on the high temperature side flow path 4. Discharge side pressure gauge 7 is provided between the heat exchanger 6 and the heat exchanger 6, and a suction side pressure gauge 8 is provided between the heat exchanger 6 and the compressor 2 on the low temperature side flow path 5. On the downstream side, a valve 9 for connecting a vacuum pump is provided. And the simulation component 10 which circulates the refrigerant | coolant containing refrigeration oil is comprised by the above components.

As the test conditions, the suction side pressure Ps was 0.4 MPa, the discharge side pressure Pd was 3.3 MPa, the heat exchanger inlet temperature Td was 110 ° C, and the heat exchanger outlet temperature Ts was 30 ° C. Using isobutane (R600a) as a refrigerant, the test was carried out by mixing sample oil (total amount of (A) component and (B) component) and the amount of the refrigerant by 400 g.

Example  1 to 8, Comparative example  1 to 7

Refrigerator oil containing (A) base oil and (B) specific organic compound shown in Table 1 were manufactured, and the evaluation method evaluated. The results are shown in Table 1.

In addition, the symbol which shows the (A) component and (B) component used here is as follows.

A-1; Polypropylene glycol dimethyl ether (40 ℃ viscosity; 46 mm 2 / s)

A-2; Polyethylene glycol polypropylene glycol copolymer dimethyl ether (40 ℃ viscosity; 100 mm 2 / s)

A-3; Ester of pentaerythritol with a 1: 1 mixture of 2-ethylhexanoic acid / 3,5,5-trimethylhexanoic acid (viscosity at 40 ° C .; 65 mm 2 / s)

A-4; Poly-α-olefin (40 ° C. viscosity; 63 mm 2 / s)

A-5; Alkylbenzene (40 ° C viscosity; 38 mm 2 / s)

A-6; Paraffinic mineral oil (40 ℃ viscosity; 90 mm 2 / s, sulfur content 5 ppm by mass or less)

A-7; Naphthenic mineral oil (40 ℃ viscosity; 10 mm2 / s, sulfur content 107 mass ppm)

A-8; Naphthenic mineral oil (40 ℃ viscosity; 56 mm2 / s, sulfur content 3000 mass ppm)

B-1; Benzothiophene (sulfur content 23.9 mass%)

B-2; Dibenzothiophene (sulfur content 17.4 mass%)

B-3; Diphenylenedi sulfide (sulfur content 29.6 mass%)

B-4; Phenothiazine (sulfur content 16.1 mass%)

B-5; Diphenyl sulfide (sulfur content 17.2 mass%)

B-6; Dioctyl diphenyl sulfide (sulfur content 7.8 mass%)

B-7; Dioctyl polysulfide (sulfur content 39 mass%)

B-8; Tricresyl phosphate

The novel refrigeration oil composition of the present invention is free from environmental problems such as destruction of the ozone layer and global warming, and can maintain lubrication performance over a long period of time, and does not block the capillary tube in the refrigeration cycle. Therefore, it can be used suitably as refrigeration, car air conditioner, hot water supply, floor heating, etc. for air conditioners, refrigerators, gas heat pumps (GHP), vending machines, showcases, and the like.

Claims (9)

(A) a base oil comprising at least one member selected from polyalkylene glycol, polyol ester, poly-α-olefin, alkylbenzene and mineral oil, (B) Content of sulfur is 35 mass% or less, benzothiophene, dibenzothiophene, phenothiazine, benzothiapyran, thiapyran, dibenzothiapyran, diphenylenedisulfide, diphenyl sulfide, and these At least one organic sulfur compound selected from alkyl derivatives of (C) a refrigerant comprising at least one selected from carbon dioxide, hydrocarbons and ammonia The refrigeration oil composition containing these, Comprising: The content of total sulfur is 0.01-0.1 mass% with respect to the total amount of (A) component and (B) component. The refrigerator oil composition of Claim 1 whose viscosity in 40 degreeC of (A) base oil is 3-1000 mm <2> / s, and sulfur content is 200 mass ppm or less. The refrigeration oil composition according to claim 1 or 2, further comprising an antioxidant, an acid trapping agent, and an antifoaming agent. The refrigerator oil composition of Claim 1 or 2 which does not contain a phosphorus extreme pressure agent. delete delete delete delete delete

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